2 Phase flow simulation in a T-junction microchannel
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Hi. I am doing a transient laminar flow simulation to get the slug flow of 2 phase immiscible liquids in a t junction micro channel using VOF model. Its a simple 2d geometry and surface tension modelling is enabled. Whenever my timestep advances I get an error stating that the global COurant number is greater than 250. I reduced the time step to values as low as 1e-5. Still the problem persists. I also reduced the UR factors and increased the iterations per time step. (Pressure-0.2, Density-0.5, Body forces-0.5 Momentum- 0.3 As seen in some forum). The velocity seems to be fine at time 0 but drops to zero as soon as the timestep advances. I have included the snapshot. Can somebody help me?
http://postimg.org/image/k7mjf5k71/ http://postimg.org/image/k7mjf5k71/ |
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Thanks for the reply. Its 0.8mm microchannel t-junction. I have two opposite inlets one of kerosene and other water. Both with velocity ranging from 0.02-0.1 m/sec. So what would be the estimated time step size?
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Would it be such a mayor inconvenience to reduce the time step size to lets say 10e-8s just to see if the error is really related to the time step size?
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Could you please give more input about your Simulation?
-Reference density -I think you are using a tracking method (explicit that's why CFL-dependency) Geo-REconstruct -Are both phases well separated like a normal slug flow simulation or do they interpenetrate each other? Are small bubbles and liquid entrainment expected to occur or not? -Which interpolation of Pressure are you using? -Reference Location of the operating Pressure -Operating Pressure.. |
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vof modeling in micro channel in fluent
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i am simulating a model with two vents and one outlet.the water patched into the main chamber and air can goes in and out from two vents. i want to simulating water flow in channel. i dont have any parameters in vents what is the best boundary condition for them? the vents are in the atmosphere pressure but the whole model is rotating so i dont know the gauge pressure=0 in correct for these vents or not? i use the out flow for outlet which it is incompatible with pressure boundaries. i cant see the right flow in channel is there any one could help me? the residuals cant decrease enough and continuity residuals are in order of 10 i appreciate your recommendations |
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